MATLAB: How to set the pixel values to 1 and o’s based on some threshold values

color segmentationdigital image processing

Eg. if redpixel>th and redpixel>green and greenpixel>blue then mark all the pixel values as 1 otherwise to 0

Best Answer

binaryimage = rgbimage(:, :, 1) > threshold         ... red pixels greater than threshold
              &                                     ... AND
              rgbimage(:, :, 1) > rgbimage(:, :, 2) ... red greater than green
              &                                     ... AND
              rgbimge(:, :, 2) > rgbimage(:, :, 3); ... green greater than blue

Or in one line:

binaryimage = rgbimage(:, :, 1) > threshold & rgbimage(:, :, 1) > rgbimage(:, :, 2) & rgbimge(:, :, 2) > rgbimage(:, :, 3);

Related Solutions

MATLAB: How to plot smaller o’s using plot(x,y,’o’)

Do you really need to plot all 85,000 individual markers and have them visible simultaneously? What fraction of the number of pixels on your screen does each pixel take up? You can check this by querying the ScreenSize property of the groot object.

Setting a MarkerSize of 0.05 means you want each marker to take up 1/20 of a point. A point is 1/72 inch.

If you do need to plot all of them at once, I would change the axes limits to only display a small portion of the plotting region at a time or plot them using '.' as your marker instead of 'o'. Otherwise it's going to be really difficult to interpret your data, like looking at a picture of a desert and hoping to draw conclusions from the appearance of individual grains of sand.

MATLAB: How can i convert black backgorund to white

Try this:

clc;    % Clear the command window.
workspace;  % Make sure the workspace panel is showing.
close all;
clear all;
format long g;
format compact;
fontSize = 20;
% Read in a color demo image.
folder = 'C:\Users\kalaivaani\Documents\Temporary';
baseFileName = 'bgrnd.JPG';
% Get the full filename, with path prepended.
fullFileName = fullfile(folder, baseFileName);
if ~exist(fullFileName, 'file')
  % Didn't find it there.  Check the search path for it.
  fullFileName = baseFileName; % No path this time.
  if ~exist(fullFileName, 'file')
    % Still didn't find it.  Alert user.
    errorMessage = sprintf('Error: %s does not exist.', fullFileName);
    uiwait(warndlg(errorMessage));
    return;
  end
end
rgbImage = imread(fullFileName);
% Get the dimensions of the image.  numberOfColorBands should be = 3.
[rows, columns, numberOfColorBands] = size(rgbImage);
% Display the original color image.
subplot(2, 2, 1);
imshow(rgbImage);
axis on;
title('Original Color Image', 'FontSize', fontSize);
% Enlarge figure to full screen.
set(gcf, 'units','normalized','outerposition',[0 0 1 1]);
% Extract the individual red, green, and blue color channels.
redChannel = rgbImage(:, :, 1);
greenChannel = rgbImage(:, :, 2);
blueChannel = rgbImage(:, :, 3);
% If background is less than 45, say it's background.
% Adjust the value as needed to achieve what you want.
thresholdValue = 45;
mask = redChannel <= thresholdValue & greenChannel <= thresholdValue & blueChannel <= thresholdValue;
% Display the mask image.
subplot(2, 2, 2);
imshow(mask);
title('Mask Image', 'FontSize', fontSize);
% Initialize the masked channels.
maskedRed = redChannel;
maskedGreen = greenChannel;
maskedBlue = blueChannel;
% Do the masking - make white where it was black.
maskedRed(mask) = 255;
maskedGreen(mask) = 255;
maskedBlue(mask) = 255;
% Recombine separate masked color channels into a single, true color RGB image.
maskedRgbImage = cat(3, maskedRed, maskedGreen, maskedBlue);
% Display the masked color image.
subplot(2, 2, 3);
imshow(maskedRgbImage);
title('Masked Color Image', 'FontSize', fontSize);

Best Answer

Related Solutions

MATLAB: How to plot smaller o’s using plot(x,y,’o’)

MATLAB: How can i convert black backgorund to white

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